(a) Technical Field
Exemplary embodiments of the invention relates to a power supply device. In particular, the exemplary embodiment relates, for example, to a power supply device to which primary-side regulation (PSR) is applied.
(b) Description of the Related Art
A range of an output voltage of a power supply device may vary according to a load. For example, when the power supply device supplies power to a load where a plurality of LEDs are connected in series, an output voltage range is changed according to the number of LEDs.
A control IC of a PSR power supply device receives a sense voltage that is proportional to an output voltage. In this case, a sense voltage range is set in the control IC. For example, a sense voltage range of 0.8 V to 3 V is set in the control IC, the minimum level of the sense voltage is controlled to be 0.8 V, and the maximum level of the sense voltage is controlled to be 3 V. When the maximum level of the sense voltage exceeds 3 V, an over-voltage protection operation is activated.
However, when the output voltage is changed according to a load, a problem may occur if the sense voltage is controlled by the voltage range set in the control IC. For example, when the number of LEDs connected in series to the PSR power supply is increased and thus the output voltage is increased, the sense voltage is also increased and thus the over-voltage protection operation may be activated even in a normal condition.
The sense voltage range is widened as the output voltage range is widened, and a conventional PSR power supply device cannot sufficiently cover the sense voltage range. Thus, when the output voltage is changed, a design of the control IC also needs to be changed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.